Rotary feed and distributor valves and operating mechanism therefor



1958 G. NlEMlTZ 2,824,670 7 ROTARY FEED AND DISTRIBUTOR VALVES ANDOPERATING MECHANISM THEREFOR Original Filed July 25, 1954 4 2Sheets-Sheet 1 FIG. 8

Mum

.fi INVENTOR ATTCIDRNEYS Gerhard Niemitz Feb. 25, 1958 G. NlEMlTZ2,824,670 RQTARY FEED AND DISTRIBUTOR VALVES AND OPERATING MECHANISMTHEREFOR Original Filed July 23, 1954 2 Sheets-Sheet 2 o w 8, J) z, a bil 3 In c n o v I!) .2 w

I N c 2 L o u 0 x i F: 2 I $3 INVENTOR Gerhard Niemitz ATZI'ORNEYSUnited States Patent RGTARY FEED AND DISTRIBUTOR VALVES AND OPERATINGMECHANISM THEREFGR Original application July 23, 1954, Serial No.445,305.

Divided and this application February 29, 1955, Serial No. 568,592

5 Claims. (Cl. 22276) This invention relates to improvements in rotaryfeed and distributor valves and operating mechanism therefor, moreparticularly for use in connection with suspension or contact type heatexchangers for preheating dust-like materials, such as the chargingstock for cement kilns with the hot gases from the kiln.

The present application is a division of my pending application Ser. No.445,305, filed July 23, 1954, for Suspension Type Heat Exchanger andMethod of Heating Finely Divided Solids.

The preheater for finely-divided solid materials, as disclosed in saidpending application, comprises a towertype heat exchanger, including aseriesof chambers provided with bafiles over which the fine solidmaterial drops in succession from an elevated feed bin, thefinely-divided material passing through a series of air locks or rotaryvalves downwardly through the tower to the point where it enters theinlet of a cement kiln, for example. In this construction the gastravels in parallel flow with the finely-divided solid material throughthe series of chambers, at the bottom of each section of which the gasis forced to make a sharp 180 turn, so that most or" the dust or solidmaterial is separated therefrom. After leaving one chamber or section,the gas travels upward to the top of the next higher section of theseries where its direction of flow is reversed and it. again travels inparallel fiow downwardly with the fine material being preheated. Theintimate contact and separation of highly-heated gas and finely-dividedsolid is accomplished in each of the series of zones or sections. Afterthe gas leaves the final heat transfer compartment or section, it isconducted through a cyclone type dust collector for the removal of anyfinely-divided material which may have been carried by the gas stream.These cyclone separators discharge the dust'through air locks into amixing zone where it is mixed with dust previously separated from thegas stream in the first zone of the series, in the direction of solidsflow. This mixing compensates for any segregation of solid particles dueto difference in sizing in the series of zones, since all material mustpass through the same heat transfer sections or compartments.

In this heat exchanger the preheated dust separated out in each zone orsection is passed from that section through a rotary feed valve or airlock, constructed according to the invention, into a downwardly-flowinggas stream of higher temperature in the next lower section of theseries. The heat exchange tower is advantageously divided into similarparallel sections where parallel streams of hot gases respectivelycontact separate streams of downwardly-flowing solid particles ofmaterial to be preheated. In this construction the two streams of gasare preferably mingled after one or more heat exchange contacts and thendivided again into streams for separate individual contacts.

According to the present invention the improved construction includesmeans for automatically operating 2,824,53 Patented F eh. 25, 1958 theair locks or rotary feed valves to prevent clogging or injury to theequipment. These rotary valves or air locks are protected by a gridagainst the entry of large pieces of hard material which mayaccidentally drop from the contact shelves in the heat-exchange zones.These pieces of hard material may, for example, be pieces of fire brickor pieces of condensed alkali or calcined materials being processed. Anysmaller pieces which pass through the protecting grid and which mayaccidentally jam the leading edge of the rotary gate are automaticallyfreed by reversal of the direction of rotation of the rotary gate orlock. This permits the freed piece to drop into the bottom of the gatepocket so that it can be discharged to the next heat-exchange zone orsection.

The feed valves and mountings are preferably constructed ofhigh-temperature alloy metals and these structures are protected againstexcessive heat by forced air cooling, the air for cooling the rotarygate or valve being directed through the center of the rotor. The gatesare so constructed that very little gas leakage is encountered, but inany case, there is very little leakage because the draft differentialbetween the succeeding heat-exchange stages or sections is very low.This low difl'erential permits of a very liberal clearance between thegate or valve rotor and the housing thereof.

Electrically-operated means is provided for reversing the direction ofrotation of the rotary gates or valves, as described more in detailhereinafter.

The improved apparatus of this invention includes other features anddetails which are described hereinafter in connection with theaccompanying drawings which illustrate one embodiment of the invention.In the drawings:

Fig. 1 is an enlarged broken vertical sectionalview of a portion of aheat-exchange tower showing the details of the rotary valve or gateconstruction; and i Fig. 2 is a diagrammatic view including a wiringdiagram for the automatic operation of the feed or distributor valvesaccording to the invention.

Referring to Fig. l, the heat-exchange tower is illustrated inconnection with the supply of finely-divided or. pulverized dust-likecharging stock or raw-material to a cement kiln it; of the rotary type.The inlet end of the kiln 10 is shown directly connected to a feed chute11 having an arcuate or curved slanting bottom. The feed chute 11 leadsinto the lower portion of a'heatexchange tower 12 having a steel-worksupporting frame including columns 13. While the heat-exchange tower hasa steel-work frame, its walls and various structures forming theheat-exchange compartments, passages and gas ducts are made ofrefractory material. I The tower 12 is generally rectangular incross'section and provided with a vertical series of heat-transferchambers provided with horizontal feed valves, so that a wide band offinely-divided material is delivered by each feed valve at apredetermined rate depending upon the rate' of rotation of the valves.Fig. 1 shows only the lower portion of the tower in connection with apair of heat transfer chambers 26 and 27; In each chamber the dustlikematerial falls on and slides down the sloping surfaces ofalternately-arranged shelves or baffles 19 until it reaches the lowerend of the chamber where it collects above rotary valves or gates 28 and29, respectively. These gates or feed valves function to supplyfinely-divided heated material to the kiln 10 through inlet 11. Similarrotary valves supply material to the chambers 26 and 27 from higherchambers in the tower.

The finely-ground raw material for making cement is heated by directtransfer from the high temperature gases produced from burning the rawmaterial to Portland cement in the kiln 10. These gases-at a very hightempera ture are discharged from the material inlet end of the kilnthrough the chute 11 of relatively large cross-sectional area directlyinto a relatively large rectangular-shaped passageway 30, extendingtransversely of the tower between the heat-exchange compartments orchambers 26 and 27. The passageway 39 is defined by transverse walls 31,at the top of which the high temperature gases from the passageway 30divide and flow over the walls 31 into the respective chambers 26 and 27in direct contact with the fine powdered raw material deliveredthereinto at the top by rotary distributor valves. The raw material is,therefore, preheated while it is directly in suspension in the hightemperature gases, the alternating baffles 19 cansing the gases andsuspended raw material to change their direction of flow as they movedownwardly together through the chambers 26 and 27.

The walls 31 cooperate with opposite walls 32 to define the chambers 26and 27, respectively, and the walls 32 cooperate with the respectiveside walls 33 to provide passageways 34 and 35, respectively at oppositesides of the tower for the flow of high temperature gases from therespective chambers 26 and 27. As the high temperature gases in thechambers 26 and 27 reach the lower end of these chambers with theirsuspended highly-heated raw material, the gases make an abrupt 180 turnaround the lower ends of the walls 32 and flow respectively upwardlythrough the gas passageways 34 and 35 to the top of the walls 32 overwhich they overflow into and downwardly through the next higherheat-exchange chambers in the tower, constructed like the chambers 26and 27.

The heat-exchange operation carried out in the tower 12 takes advantageof the parallel flow of high temperature gases and pulverized rawmaterial. This parallel flow takes place in each section of theheat-exchange tower. At the bottom of each section the stream of gas isforced to make a sharp 180 turn, so that most of the dust is separatedfrom the gas stream. From this point the gas travels upwardly to the topof the next heatexchange section where it again travels in parallel flowwith the material to be heated. The heat-exchange sections and thegeneral structure of the tower and its passages are of such a naturethat the gas velocity is kept low so that the proportion of dust in therising gas streams is relatively low. Any dust which is carried up withthe gas stream in any instance is returned to the dust or fine rawmaterial traveling downward in the next higher heatexchange chamber orzone.

Inspection and repair doors 52 are provided at least on one side of thetower directly above the position of each of the rotary distributorvalves or gates so that such gates may be inspected or repaired. If thedistributor valve or gate 29, for example, should become stopped up orotherwise go out of operation, this would be noticed through the door52, and the rotary valves directly above could be stopped temporarily sothat there would not be an accumulation of raw material above the gate29, to any great extent. In case of serious difficulty, the flow of rawmaterial to and the flow of gas through the tower may be discontinuedfor the purpose of making repairs, the hot gases at that time being sentthrough a bypass leading from the passageway 30 and delivering the hotgases directly into a stack.

In order to facilitate inspection and repair of the rotary valves atvarious levels in the tower, the tower is provided with platforms 55which also serve to support the motors and other equipment for operatingthe rotary distributor valves; one motor 56 and its control 57 are shownin Fig. 1 for operating the rotary valve 28.

Fig. 1 shows the preferred type of construction for the rotary valvesand the associated mountings therefor arranged in the refractorybrickwork of the tower. All of the rotary valves may be constructedalike as illustrated by the structure shown in Fig. 1 for the rotaryvalve 29. In this view the motor, as shown, comprises a longitudinalbody portion provided with an axial opening 58 through which cooling airis forced by a fan or blower, not shown. The body includes a number ofradially-extending blades 59 defining intervening pockets for thereception of finelydivided material to be transferred through the valvestructure to the next lower section or to the chute 11 leading to thekiln.

The valve rotor 29 is operatively associated with a metal mounting setin the refractory work of the tower and including hollowtransversely-extending spaced side sections 60 having arcuate portionsfitting over the upper side portions of the rotor, and downwardly andinwardlysloping opposite upper surfaces, along which the finelydividedmaterial flows to the rotor. The mounting structure also includes a gridor grating 61 over the opening in the mounting and arranged to catch andexclude large particles from entry to the rotor. Cooling air from theblower referred to, and not shown, is forced through the hollow elements60 of the mounting to prevent them from softening or melting. All of themetal elements of the rotary valve structure, including the mounting,are made of high temperature alloy metals. When any large particles ofmaterial or pieces of the brick, for example, are found on the gratingsor grids 61, they may be raked out through the adjacent door 52. Therotors, such as 29, are provided with hollow end shaft sections, whichextend through the refractory side walls of the tower and may be open tothe atmosphere at one end and connected to a blower at the other end.The blower or blowers may be located on one or more of the towerplatforms 55.

Fig. 2 shows diagrammatically the arrangement for operating the rotarydistributor valves, such as 28, 29, etc., this view showing a singleunit for operating the motor 56 (Fig. 1) for driving the rotary valve28, preferably through a clutch and sprocket. The wiring arrangement andrelays shown in Fig. 2 may be housed and included in the control 57,having a double-throw contactor arm 57 operated by a prong on asprocket. The motor 56 is indicated. diagrammatically in connection withits windings, and in association with relays 62 and 63 for connectingthe motor to a three-wire current supply 64 for respectively operatingthe motor in either direction of rotation. The motor 56, with thecontrol shown, will continue to operate in the same direction so long asit does not become overloaded. When a piece of solid material catchesbetween the edge of one of the blades 59 and the mounting 60, the rotorwill be stopped and the motor 56 will become overloaded, which will, forexample, open an overload switch 65 and de-energize the relay 62, asshown, thereby cutting off the power for rotation of the motor in thatdirection. As the relay 62 is de-energized, it closes a switch 66,thereby permitting current to flow from one of the current-supply lines64 through a hand switch 67, the switch 66, an overload switch 68, andthe coil of relay 63 through a switch of a double-throw switch unit 69,closed by the motor, to the neutral line of the power supply 64. Whenthe relay 63 is energized, the current-supply leads 64 are connectedthrough the upper three switches of the relay to operate the motor 56 inthe opposite direction to the one in which it was previously operated.This will permit any solid piece of material between a rotor blade andthe mounting 60 to fall into a cavity of the rotor and thereby bedischarged through the rotary valve. The relay 63 also closes a switch71 which applies a holding current on the relay 63, since the motor,when reversed, will open switch 70 and close a switch 74.

Eventually the overload switch 65 closes, but since it is in series witha now open switch 72 of relay 63, it has no effect on the system.However, if the motor should now become overloaded because of thejamming of the rotary valve 28, for example, the overload switch 68 willopen, the relay 63 will be de-energized and relay 62 energized. When themotor 56 was previously reversed, it shifted the double-throw switchunit 69 to open switch 70 and close switch 74. As room as the relay 62is energized, the motor is rotated in the opposite direction by currentsupplied through the upper three switches of the relay 62. As this relaycloses, the switch 66 is opened, and a switch 75 is closed to provide aholding circuit on the relay 62 through switches 65 and 72. The switchunit 69 is shifted by an arm 57' which is rocked one way or the other bya spring prong 76 carried by a sprocket 77 mounted on the shaft of therotary valve 28 and driven by a drive chain from the motor 56.

While the foregoing system is sufficient in most instances for takingcare of the reversal of rotation of the rotary valves of theheat-exchange tower installation, modified forms of controls may beprovided. For example, a switch may be provided directly in series withthe hand switch 67 for interlocking the control with other motors. Theoverload switches 65 and 68, are shown diagrammatically responsive tooverloads in the respective pairs of power-supply lines to the motor.These overload switches are conventional.

It is to be understood that switches 70 and 74 may be shifted by anymeans actuated by the slowly-rotating sprocket 77, operated by-the motor56, so that the doublethrow switch unit 69 is shifted in a direction forlater reversing the direction of rotation of the motor. If the motor isstopped by opening the manual switch 67, when under control of relay 63,the double-throw switch unit 69 is in position for closing the switch74, ready to start the motor operating in the direction controlled bythe relay 62.

If the particles supplied to or condensed in the heatexchange operationare sufliciently large, it is possible that the motor or motors mayreverse a number of times during a days operation. It is to beunderstood that a control system, such as that shown in Fig. 2, orequivalent thereto, is provided for the motors or other driving or powermeans for all of the rotary valves of the heatexchange tower.

Iclaim:

1. In an apparatus of the type described, a rotary valve typedistributor for feeding and distributing finely-divided material, anelectric motor for driving said rotary distributor', a pair of similarelectric wiring circuits for respectively operating said motor inopposite directions,

means responsive to an overload in the circuit in use for shifting thecurrent supply to the motor to the other circuit, a relay in each ofsaid circuits, and means responsive to the rotation of the motor when itis reversed for preparing a circuit for energizing the relay in themotor operating circuit not in use.

2. A rotary valve type distributor, comprising a mounting structureincluding spaced horizontally-extending side sections having arcuateinner surfaces, a rotor mounted for rotation between said arcuatesurfaces and including radially-extending blades defining pockets forreceiving finely-divided solid material, said side sections and rotorbeing hollow for receiving a cooling fluid, said side sections eachhaving a downwardlyand inwardly-sloping surface extending to the upperportion of the rotor for directing finely-divided solid material to thepockets of the rotor, means for rotating the rotor, and means forreversing the direction of rotation of the rotor when rotation of therotor in one direction is stopped by material entering one of itspockets.

3. A rotary valve type distributor as claimed in claim 2, including agrating extending over the rotor for excluding larger-sized pieces ofmaterial from entry into the rotor.

4. An apparatus as claimed in claim 1, characterized in that each relayincludes a holding switch, and a holding circuit connected into theholding switch for keeping the relay in energized position whenoperated.

5. A rotary valve type distributor as claimed in claim 2, characterizedin that the means for rotating the rotor includes an electric motor, apair of similar electric wiring circuits for respectively operating saidmotor in opposite directions, means responsive to an overload in thecircuit in use for shifting the current supply to the motor in the othercircuit, a relay in each of said circuits, and means responsive to therotation of the motor when it is reversed for preparing a circuit forenergizing the relay in the motor operating circuit not in use.

References Cited in the file of this patent UNITED STATES PATENTS1,558,668 Carter Oct. 27, 1925 2,594,974 Mylting Apr. 29, 1952 2,599,978Davis et al. June 10, 1952

